1. Field of the Invention
The present invention relates to methods and apparatus for filtering content delivered to end users over a wide-area network, for example, filtering to prevent inappropriate adult-oriented materials from being accessed by children using public or privately-shared terminals.
2. Description of Related Art
Various methods are known for detecting and restricting access to undesired information distributed over wide area networks. Such methods may employ automatic keyword analysis to identify and classify written materials, and pattern recognition for classifying images. Such methods, however, suffer from the deficiency of being easily fooled or inadvertently misclassifying information, and therefore being over inclusive or under inclusive. For example, authors of “spam” messages may readily avoid spam filters by inserting a few random characters in a text string, rendering it unrecognizable to a filter but still easily understood by a human being. At the same time, it is not generally desirable for an automatic filter to screen out every bit of questionable information, as this would impede the benefit of connecting to a wide area network in the first place.
Likewise, image pattern recognition may not be able to distinguish tasteful artistic or educational images from obscene materials. Pattern recognition algorithms may also be fooled to overlook targeted classes of images by including random information in an image, or by breaking an image into pieces. Meanwhile, a human reviewer may have little difficulty in discerning an intended obscene image that an automatic pattern recognition algorithm is unable to recognize. Consequently, automatic filtering methods are often relatively ineffective in screening out undesired content, such as obscene or pornographic content, or unsolicited “spam.”
Even apart from the effectiveness of filtering algorithms, a further problem arises in the operation of network terminals that are accessed by different classes of people. For example, a terminal may be operated at a library or other public area for use by patrons. Such patrons may include adults or children, and it may be desirable to screen certain content for children but not for adults. Essentially the same problem may be encountered in a home, where a single terminal may be shared by members of the household of various different ages or information requirements. One or more persons, for example, a librarian, may be responsible for ensuring that the public terminal is not used inappropriately, while still being available to access unfiltered (or differently-filtered) content by qualified persons. Such persons may find that turning the filtering on or off, or otherwise adjusting filtering levels for the public terminals under their control, is too time-consuming and inconvenient.
It is desirable, therefore, to provide a methods and apparatus for network filtering that overcomes these deficiencies.